The present invention is a development and improvement to reamers of the type used in joint replacement surgery and in particular for the recently developing field of minimally invasive joint surgery.
Factors such as the perpetual pressure to improve the standard of patient care, the increasing costs of surgery, a population trend that has an increasing proportion of elderly persons suffering from osteoarthritis, have initiated change to the nature of joint replacement. The main areas of change in surgery have three primary goals: first, to minimize the trauma of surgery to individual patients; second, to diminish the time that the patient is required to remain in hospital after surgery; and third, to reduce the time of surgery. All of the above may be accomplished by reducing the size of incision, something often described as minimal access or minimal invasive joint surgery.
The smaller incision and the associated change in surgical technique that cuts fewer soft tissue structures reduces the injury to the patient caused by the operation and thereby allows a shorter recovery time. The procedure is may be made quicker in certain respects when a smaller incision is made, due to the lower number of blood vessels and soft tissue structures damaged. Further, fewer repairs are required when closing the incision after the joint replacement.
A consequence of a smaller incision is that it can be harder for the surgeon to have a clear view of the operative site. Further, implants and instruments pass closer to or are in fact touching the edges of the wound more often. This contact with the edges of the incision may create an associated risk of infection or of soft-tissue injury. To minimize this risk, a trend exists to make instruments smaller and smaller and/or of different geometries as described in pending applications Ser. Nos. PCT/IB01/02676, U.S. 60/372,285, and U.S. 60/376,479, of the assignee, all of which are fully incorporated herein and relied on.
One approach at minimizing the injury to the patient during such bone operations has been to reduce the width of the front profile of a standard acetabular reamer (which has also been referred to as the static profile in the referenced cases cited immediately above) so that the reamer can pass more easily through a smaller incision. However, such designs generally compromise the cutting surface of the reamer in that there are less cutting sites available for the purpose of cutting bone.
What is needed therefore, is a tool for use in performing minimally invasive surgery having a large dynamic profile while not compromising the total number of cutting sites on the tool.